save game information between scenes and on application close and exit.

Let’s say I had a users total points, credits, whatever numerical value displayed in the top right of every scene, how do I keep it from scene to scene, and say someone exits out of the game, how do I save their points so it’s the same when they open it again?

The most simplistic way is to use Player Prefs:

using UnityEngine;
using System.Collections;

public class test : MonoBehaviour {

 	void ExampleSave() {
		PlayerPrefs.SetInt("Player Score", 10);
	}

	void ExampleLoad() {
		if (PlayerPrefs.HasKey("Player Score")) 
			print(PlayerPrefs.GetInt("Player Score"));
	}
}